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Re: [PATCH] fast-export: avoid NULL pointer arithmetic




On Fri, May 11, 2018 at 6:49 AM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
> Junio C Hamano <gitster@xxxxxxxxx> writes:
>
>> René Scharfe <l.s.r@xxxxxx> writes:
>>
>>>> But it somehow feels backwards in spirit to me, as the reason why we
>>>> use "void *" there in the decoration field is because we expect that
>>>> we'd have a pointer to some struture most of the time, and we have
>>>> to occasionally store a small integer there.
>>>
>>> Yes, fast-export seems to be the only place that stores an integer as
>>> a decoration.
>>
>> With the decoration subsystem that might be the case, but I think
>> we have other codepaths where "void * .util" field in the structure
>> is used to store (void *)1, expecting that a normal allocation will
>> never yield a pointer that is indistinguishable from that value.
>
> I was looking at a different topic and noticed that bisect.c uses
> commit->util (which is of type "void *") to always store an int (it
> never stores a pointer and there is no mixing).  This one is equally
> unportable as fast-export after your fix.
>

In both cases we should be able to use commit-slab instead of
commit->util. We could go even further and kill "util" pointer but
that's more work.
-- 
Duy